Non-aqueous secondary batteries (hereinafter, also referred to simply as “secondary batteries”), such as lithium ion secondary batteries, have characteristics such as compact size, light weight, high energy density, and the ability to be repeatedly charged and discharged, and are used in a wide variety of applications. A non-aqueous secondary battery generally includes battery components such as a positive electrode, a negative electrode, and a separator that isolates the positive electrode and the negative electrode from one another and prevents short circuiting between the positive and negative electrodes.
There are cases in which a battery component including a functional layer for imparting desired performance on the battery component is used in a secondary battery. Specifically, a separator obtained by forming a functional layer on a separator substrate or an electrode obtained by forming a functional layer on an electrode substrate including an electrode mixed material layer on a current collector may, for example, be used as a battery component.
In recent years, there has been much activity focused on enhancing functional layers with the aim of further raising secondary battery performance. In one specific example, an electrode has been proposed that is obtained by forming a functional layer having the ability to capture water or hydrogen fluoride (HF) on an electrode substrate (for example, refer to PTL 1). A functional layer described in PTL 1 contains inorganic particles having a prescribed BET specific surface area and improves rate characteristics and cycle characteristics of a secondary battery as a result of these inorganic particles trapping moisture and hydrogen fluoride in the secondary battery.